REGR: merge with 3rd party EA's can sometimes raise ValueError

[lukemanley]

• closes BUG: ExtensionArray no longer can be merged with Pandas 2.2 #57316
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/v2.2.1.rst file if fixing a bug or adding a new feature.

[phofl]

can we test this somehow? We have "test_downstream.py" for this?

[lukemanley]

would you be ok with just testing against a pyarrow list type? e.g. this raises a ValueError:

import pyarrow as pa
import pandas as pd

arr = pd.array([[1], [2, 3]], dtype=pd.ArrowDtype(pa.list_(pa.int64())))

pd.Index(arr).is_monotonic_increasing  # ValueError

[phofl]

Yep that’s fine

[phofl]

I just want to avoid that someone removes the ValueError and the tests don’t fail

[lukemanley]

thanks, test added

[phofl]

Thx @lukemanley

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 2.2.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 2e0ef79dd48b13045ff3539df895c3b647c25403

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am "Backport PR #57333: REGR: merge with 3rd party EA's can sometimes raise ValueError"

4. Push to a named branch:

git push YOURFORK 2.2.x:auto-backport-of-pr-57333-on-2.2.x

5. Create a PR against branch 2.2.x, I would have named this PR:

"Backport PR #57333 on branch 2.2.x (REGR: merge with 3rd party EA's can sometimes raise ValueError)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.